In-Can Stabilizers

Abstract

The invention relates to the use of highly sterically hindered nitroxyl radicals as in-can stabilizers for UV-curable resins. The present invention further relates to the use of quinone methides as in-can stabilizers for UV-curable resins.

1 . A method as for in-can stabilization of UV-curable resins which comprises adding to compositions comprising the UV-curable resins stable highly sterically hindered nitroxyl radicals of the formulae I or II  
     
       
         
         
             
             
         
       
     
     wherein 
 R a , R b  R c , R d  are independently of each other optionally substituted C 1 -C 18 alkyl or benzyl, optionally substituted C 5 -C 12 cycloalkyl or C 6 -C 10 -aryl; or R a , R b  R c , R d  together with the carbon atom form a C 5 -C 12 cycloalkyl ring,  
 A and D are groups required to complete the open chain nitroxyl radical;  
 R e , R f , R g , R h  are independently of each other optionally substituted C 1 -C 18 alkyl or benzyl, optionally substituted C 5 -C 12 cycloalkyl or C 6 -C 10 -aryl; or R e , R f , R g , R h  together with the carbon atom form a C 5 -C 12 cycloalkyl ring, with the proviso that at least one group is different from methyl;  
 T is a group to complete a ring nitroxyl radical.  
 
   
   
       2 . A method according to  claim 1  to improve the storage stability by preventing the geling of a resin being composed of monomers-, oligomer- or polymer-molecules that have at least one ethylenically unsaturated group.  
   
   
       3 . The method according to  claim 1 , wherein the compounds of formula I are open chain stable highly sterically hindered nitroxyl radicals of the formulae Ia-Ie  
     
       
         
         
             
             
         
       
     
     wherein 
 in formula Ia  
 Y is O or CH 2 ;  
 R 1  is tertiary C 4 -C 18 alkyl or C 6 -C 10 aryl, which are unsubstituted or substituted by halogen, OH, COOR 51  or C(O)—R 52  wherein R 51  is hydrogen, an alkali metal atom or C 1 -C 18 alkyl and R 52  is C 1 -C 18 alkyl; or  
 R 1  is C 5 -C 12 cycloalkyl, C 5 -C 12 cycloalkyl which is interrupted by at least one O or N atom, a polycyclic alkyl radical or a polycyclic alkyl radical which is interrupted by at least one O or N atom;  
 R 2  and R 3  are independently optionally substituted C 1 -C 18 alkyl, benzyl, C 5 -C 12 cycloalkyl or C 6 -C 10 aryl;  
 or together with the carbon atom form a C 5 -C 12 cycloalkyl ring;  
 if Y is O,  
 R 4  is OH, O(alkali-metal) C 1 -C 18 alkoxy, benzyloxy, NR 53 R 54 , wherein R 53  and R 54  are independently from each other hydrogen, C 1 -C 18 alkyl or C 6 -C 10 aryl, which are unsubstituted or substituted by halogen, OH, COOR 51  or C(O)—R 52 , wherein R 51  and R 52  is as defined above;  
 if Y is CH 2 ,  
 R 4  is OH, C 1 -C 18 alkoxy, benzyloxy, O—C(O)—(C 1 -C 18 )alkyl or NR 53 R 54 , wherein R 53  and R 54  is as defined above;  
 in formula Ib  
 Y 1  is O or CH 2 ;  
 R 5 , R 6 , R 7  and R 8  are independently of each other optionally substituted C 1 -C 18 alkyl, benzyl, C 5 -C 12 cycloalkyl or C 6 -C 10 aryl, with the proviso that not more than two are aryl; or  
 R 5  and R 6  and/or R 7  and R 8  together with the carbon atom form a C 5 -C 12 cycloalkyl ring;  
 R 9  is formyl, C 2 -C 18 alkylcarbonyl, benzoyl, C 1 -C 18 alkyl, C 5 -C 12 cycloalkyl, C 5 -C 12 cycloalkyl which is interrupted by at least one O or N atom, benzyl or C 6 -C 10 aryl, which are unsubstituted or substituted by halogen, OH, COOR 51  or C(O)—R 52 , wherein R 51  and R 52  is as defined above;  
 if Y 1  is O  
 R 10  is OH, O(alkali-metal) C 1 -C 18 alkoxy, benzyloxy, NR 53 R 54 , wherein R 53  and R 54  are as defined above;  
 if Y 1  is CH 2    
 R 10  is a group C(O)R 55 , wherein R 55  is OH, C 1 -C 18 alkoxy, benzyloxy, NR 53 R 54 , wherein R 53  and R 54  are as defined above;  
 in formula Ic  
 Q is O or NH or N—C 1 -C 18 alkyl;  
 R 11 , R 12 , R 13  and R 14  are independently of each other optionally substituted C 1 -C 18 alkyl, benzyl, C 5 -C 12 cycloalkyl or C 6 -C 10 aryl, with the proviso that not more than two are aryl; or  
 R 11  and R 12  and/or R 13  and R 14  together with the carbon atom form a C 5 -C 12 cycloalkyl ring;  
 R 15  and R 16  are independently from each other hydrogen, formyl, C 2 -C 18 alkylcarbonyl, benzoyl, C 1 -C 18 alkyl, C 5 -C 12 cycloalkyl, C 5 -C 12 cycloalkyl which is interrupted by at least one O or N atom, benzyl C 6 -C 10 aryl which are unsubstituted or substituted by halogen, OH, COOR 51  or C(O)—R 52 , wherein R 51  and R 52  is as defined above;  
 in formula Id  
 R 17  is C 6 -C 10 aryl;  
 R 18  and R 19  independently of one another are hydrogen or C 1 -C 4 alkyl;  
 in formula Ie  
 R 20  and R 21  independently of one another are hydrogen or C 1 -C 4 alkyl;  
 
   
   
       4 . The method according to  claim 1 , wherein the compounds of formula II are stable highly sterically hindered ring-nitroxyl radicals of the formula IIa-IId  
     
       
         
         
             
             
         
       
     
     wherein 
 in formula IIa  
 R 22 , R 23 , R 24 , R 25  are independently of each other C 1 -C 4 alkyl with the proviso that at least one group is different from methyl; or R 22 and R 23  and/or R 24  and R 25  form together with the C-atom to which they are bound a C 5 -C 8  cycloalkyl ring;  
 R 26 , R 27  are independently of each other H or C 1 -C 18 alkoxy; if R 26  is H, R 27  is additionally OH, —O—(C 1 -C 18 )acyl, —NHR 56  or N(R 46 ) 2 , wherein R 56  is H, C 1 -C 18 alkyl, C 5 -C 7 cycloalkyl, C 7 -C 9 phenylalkyl, C 6 -C 10 aryl or C 1 -C 18 acyl; or R 26  and R 27  together with the C-atom to which they are bonded form a cyclic ketale group  
                     
 wherein k is 0, 1 or 2 and R 57  is C 1 -C 18 alkyl, —CH 2 —OH, —CH 2 —O—(C 1 -C 18 )alkyl or —CH 2 —O—(C 1 -C 18 )acyl; if k is 2, then the two R 47  group may be different;  
 or R 26  and R 27  together form the group ═O, ═N—O—R 58  or ═N—N—R 59 R 60 , wherein R 58 , R 59 , R 60  independently are H, C 1 -C 18 alkyl, C 5 -C 7 cycloalkyl, C 7 -C 9 phenylalkyl, C 6 -C 10 aryl or C 1 -C 18 acyl;  
 R 28  is hydrogen or methyl;  
 in formula IIb  
 A is O and E is —CH 2 — or A is NR 61  and E is —C(O)—, —CH 2 — or a direct bond; wherein R 61  is H, C 1 -C 18 alkyl, C 5 -C 8 cycloalkyl, C 7 -C 9 phenylalkyl, C 6 -C 10 aryl or C 1 -C 18 acyl;  
 R 29 , R 30 , R 31 , R 32  are independently of each other C 1 -C 4 alkyl; or R 29  and R 20  and/or R 31  and R 32  form together with the C-atom to which they are bound a C 5 -C 8  cycloalkyl ring; or R 29 , R 30 , R 31 , R 32  can have inserted oxygen or bear functional groups to give compounds like  
                     
 in formula IIc  
 R 33 , R 34 , R 35 , R 36  are independently of each other C 1 -C 4 alkyl; or R 33  and R 34  and/or R 35  and R 36  form together with the C-atom to which they are bound a C 5 -C 8  cycloalkyl ring; or R 33 , R 34 , R 35 , R 36  can have inserted oxygen or bear functional groups to give compounds like  
                     
 R 37  is H, C 1 -C 18 alkyl, C 5 -C 7 cycloalkyl, C 7 -C 9 phenylalkyl, C 6 -C 10 aryl or C 1 -C 18 acyl;  
 R 38  is H, C 1 -C 4  alkyl;  
 in formula IId  
 R 39  is H, C 1 -C 18 alkyl, C 5 -C 7 cycloalkyl, C 7 -C 9 phenylalkyl, C 6 -C 10 aryl or C 1 -C 18 acyl;  
 R 40  is H, C 1 -C 4  alkyl;  
 R 41 , R 42 , R 43 , R 44  are independently of each other C 1 -C 4 alkyl; or R 33  and R 34  and/or R 35  and R 36  form together with the C-atom to which they are bound a C 5 -C 8  cycloalkyl ring.  
 
   
   
       5 . The method according to  claim 3 , wherein 
 in formula Ia    Y is O;    R 1  is tertiary C 4 -C 18 alkyl; or C 5 -C 12 cycloalkyl or C 5 -C 12 cycloalkyl which is interrupted by at least one O or N atom;    R 2  and R 3  are independently C 1 -C 18 alkyl; or together with the carbon atom form a C 5 -C 6 cycloalkyl ring;    R 4  is C 1 -C 18 alkoxy, benzyloxy or NRR 53 R 54 , wherein R 53  and R 54  are independently from each other hydrogen, C 1 -C 18 alkyl;    in formula Ib    Y 1  is O;    R 5 , R 6 , R 7  and R 8  are independently of each other C 1 -C 18 alkyl; or    R 5  and R 6  and/or R 7  and R 8  together with the carbon atom form a C 5 -C 6 cycloalkyl ring;    R 9  is formyl, C 2 -C 8 alkylcarbonyl, benzoyl, C 1 -C 18 alkyl, benzyl or phenyl;    R 10  is C 1 -C 18 alkoxy, benzyloxy, NRR 53 R 54 , wherein R 53  and R 54  are as defined above;    in formula Ic    Q is O;    R 11 , R 12 , R 13  and R 14  are independently of each other C 1 -C 18 alkyl or phenyl; or    R 11  and R 12  and/or R 13  and R 14  together with the carbon atom form a C 5 -C 6 cycloalkyl ring;    R 15  and R 16  are independently from each other formyl, C 2 -C 18 alkylcarbonyl, benzoyl, C 1 -C 18 alkyl, benzyl or phenyl;    in formula Id    R 17  is phenyl;    R 18  and R 19  independently of one another are C 1 -C 4 alkyl;    in formula Ie    R 20  and R 21  independently of one another are C 1 -C 4 alkyl    in formula IIa    R 22 , R 23 , R 24 , R 25  are independently C 1 -C 4 alkyl with the proviso that at least one group is different from methyl;    R 26 , R 27  are independently H or C 1 -C 18 alkoxy; if R 26  is H, R 27  is additionally OH, —O—(C 1 -C 18 )acyl, —NH—C 1 -C 18 alkyl; or R 26  and R 27  together with the C-atom to which they are bonded form a cyclic ketale group                          wherein k is 0, 1 or 2 and R 57  is C 1 -C 18 alkyl, —CH 2 —OH, —CH 2 —O—(C 1 -C 18 )alkyl or —CH 2 —O—(C 1 -C 18 )acyl; if k is 2, then the two R 47  group may be different;    or R 26  and R 27  together form the group ═O;    R 28  is hydrogen or methyl;    
   
   
       6 . The method according to  claim 5 , wherein 
 in formula Ia    Y is O;    R 1  is tertiary C 4 -C 8 alkyl;    R 2  and R 3  are independently of each other methyl or ethyl; or together with the carbon atom form a C 5 -C 6 cycloalkyl ring;    R 4  is C 1 -C 18 alkoxy or NH—C 1 -C 18 alkyl;    in formula Ib    Y, is O;    R 5 , R 6 , R 7  and R 8  are independently of each other methyl or ethyl; or    R 5  and R 6  and/or R 7  and R 8  together with the carbon atom form a C 5 -C 6 cycloalkyl ring;    R 9  C 2 -C 8 alkylcarbonyl, benzoyl, C 1 -C 18 alkyl or benzyl;    R 10  is C 1 -C 18 alkoxy or NH—C 1 -C 18 alkyl;    in formula Ic    Q is O;    R 11 , R 12 , R 13  and R 14  are independently of each other methyl or ethyl or phenyl; or    R 11  and R 12  and/or R 13  and R 14  together with the carbon atom form a C 5 -C 6 cycloalkyl ring;    R 15  and R 16  are independently from each other C 2 -C 8 alkylcarbonyl, benzoyl, C 1 -C 8 alkylor benzyl;    in formula Id    R 17  is phenyl;    R 18  and R 19  independently of one another are methyl or ethyl;    in formula Ie    R 20  and R 21  independently of one another are methyl or ethyl.    
   
   
       7 . The method according to  claim 1 , wherein the UV-curable resins are selected from UV curable pigmented or unpigmented urethane resins, acrylic resins, polyester resins, and epoxy resins.  
   
   
       8 . The method according to  claim 1 , wherein the UV-curable resins are components of overprint varnishes and inks.  
   
   
       9 . A method as for in-can stabilization of UV-curable resins which comprises adding to compositions comprising the UV-curable resins quinone methides of the formula III  
     
       
         
         
             
             
         
       
       wherein  
       R 1  and R 2  independently of each other are C 1 -C 18 alkyl, C 5 -C 12 cycloalkyl, C 7 -C 15 phenylalkyl, optionally substituted C 6 -C 10  aryl;  
       R 3  and R 4  independently of each other are H, optionally substituted C 6 -C 10 -aryl, 2-,3-,4-pyridyl, 2-,3-furyl or thienyl COOH, COOR 10 , CONH 2 , CONHR 10 , CONR 10 R 11 , —CN, —COR 10 , —OCOR 10 , —OPO(OR 10 ) 2 , wherein R 10  is C 1 -C 8 alkyl or phenyl.  
     
   
   
       10 . The method according to  claim 9 , wherein the UV-curable resins are selected from UV curable pigmented or unpigmented urethane resins, acrylic resins, polyester resins, and epoxy resins.  
   
   
       11 . The method according to  claim 9  wherein the UV-curable resins are components of overprint varnishes and inks.  
   
   
       12 . A method according to  claim 1 , wherein the highly sterically hindered nitroxyl radical of the formulae I or II is added as a blend with a quinone methide of the formula III  
     
       
         
         
             
             
         
       
     
     wherein 
 R 1  and R 2  independently of each other are C 1 -C 18 alkyl, C 5 -C 12 cycloalkyl, C 7 -C 15 phenylalkyl, optionally substituted C 6 -C 10  aryl;  
 R 3  and R 4  independently of each other are H, optionally substituted C 6 -C 10 -aryl, 2-,3-,4-pyridyl, 2-,3-furyl or thienyl COOH, COOR 10 , CONH 2 , CONHR 10 , CONR 10 R 11 , —CN, —COR 10 , —OCOR 10 , —OPO(OR 10 ) 2 , wherein R 10  is C 1 -C 8 alkyl or phenyl  
 wherein the blend contains 1-99 mol % of the sterically hindered nitroxyl radical of the formulae I or II and 99-1 mol % of the quinone methide.  
 
   
   
       13 . A method for increasing the storage stability of a radiation curable coating composition or ink composition by adding to the coating- or the ink composition, optionally comprising a photoinitiator, an amount of from 0.0001 to 10% by weight, based on the total amount of coating composition or ink composition a sterically hindered nitroxyl radical of formula I or II according to  claim 1 .  
   
   
       14 . A method for increasing the storage stability of an UV curable coating composition or ink composition by adding to the coating- or the ink composition comprising a photoinitiator, an amount of from 0.0001 to 10% by weight, based on the total amount of coating composition or ink composition a sterically hindered nitroxyl radical of formula I or II according to  claim 1 .  
   
   
       15 . The method according to  claim 4 , wherein 
 in formula IIb    A is O and E is —CH 2 — or A is NR 61  and E is —CH 2 — or a direct bond; wherein R 61  is H, C 1 -C 18 alkyl, C 5 -C 8 cycloalkyl or C 7 -C 9 phenylalkyl;    R 29 , R 30 , R 31 , R 32  are independently of each other C 1 -C 4 alkyl; or R 29  and R 20  and/or R 31  and R 32  form together with the C-atom to which they are bound a C 5 -C 8  cycloalkyl ring which ring may also have inserted therein at least one oxygen atom and/or be substituted by one or more oxo or alkyl groups;    in formula IIc    R 33 , R 34 , R 35 , R 36  are independently of each other C 1 -C 4 alkyl; or R 29  and R 20  and/or R 31  and R 32  form together with the C-atom to which they are bound a C 5 -C 8  cycloalkyl ring which ring may also have inserted therein at least one oxygen atom and/or be substituted by one or more oxo or alkyl groups;    R 37  is H, C 1 -C 18 alkyl;    R 38  is H, C 1 -C 4  alkyl;    in formula IId    R 39  is H, C 1 -C 18 alkyl;    R 40  is C 1 -C 4  alkyl;    R 41 , R 42 , R 43 , R 44  are independently of each other C 1 -C 4 alkyl.    
   
   
       16 . The method according to  claim 15 , wherein 
 in formula IIa    R 22  and R 24  are methyl and R 23 , and R 25  are ethyl;    R 26 , R 27  are independently H or C 1 -C 18 alkoxy; if R 26  is H, R 27  is additionally OH; or R 26  and R 27  together with the C-atom to which they are bonded form a cyclic ketal group                          wherein k is 0, 1 or 2 and R47 is C 1 -C 18 alkyl, —CH 2 —OH, —CH 2 —O—(C 1 -C 18 )alkyl or —CH 2 —O—(C 1 -C 18 )acyl; if k is 2, then the two R 47  group may be different;    or R 26  and R 27  together form the group ═O;    R 28  is hydrogen or methyl;    in formula IIb    A is O and E is —CH 2 — or A is NH or N—C 1 -C 18 alkyl;    R 29 , R 30 , R 31 , R 32  are independently of each other are methyl or ethyl; or R 29  and R 20  and/or R 31  and R 32  form together with the C-atom to which they are bound a C 5 -C 6  cycloalkyl ring;    in formula IIc    R 33 , R 34 , R 35 , R 36  are independently of each other methyl or ethyl; or R 29  and R 20  and/or R 31  and R 32  form together with the C-atom to which they are bound a C 5 -C 6  cycloalkyl ring;    R 37  is H, C 1 -C 18 alkyl;    R 38  is H;    in formula IId    R 39  is H;    R 40  is methyl;    R 41 , R 42 , R 43 , R 44  are independently of each other methyl or ethyl.    
   
   
       17 . A method for increasing the storage stability of a radiation curable coating composition or ink composition by adding to the coating- or the ink composition, optionally comprising a photoinitiator, an amount of from 0.0001 to 10% by weight, based on the total amount of coating composition or ink composition a quinone methide according to  claim 9 .  
   
   
       18 . A method for increasing the storage stability of a radiation curable coating composition or ink composition by adding to the coating- or the ink composition, optionally comprising a photoinitiator, an amount of from 0.0001 to 10% by weight, based on the total amount of coating composition or ink a blend according to  claim 12 .  
   
   
       19 . A method for increasing the storage stability of an UV curable coating composition or ink composition by adding to the coating- or the ink composition comprising a photoinitiator, an amount of from 0.0001 to 10% by weight, based on the total amount of coating composition or ink composition a quinone methide according to  claim 9 .  
   
   
       20 . A method for increasing the storage stability of an UV curable coating composition or ink composition by adding to the coating- or the ink composition comprising a photoinitiator, an amount of from 0.0001 to 10% by weight, based on the total amount of coating composition or ink composition ink a blend according to  claim 12.